Meiosis, Gametes and Fertilisation Flashcards
What are gametes?
Sex cells
What is meiosis?
Meiosis is another type of cell division, but it creates gametes.
Where are they gametes formed trough meiosis?
The ovaries and testes
What are the body cells of mammals? Haploid or diploid?
Diploid, this means that each organisms body cells has two sperm of each chromosome in its nucleus. One from its mum and one from its dad
What are gametes, diploid or haploid?
Haploid, they only have one copy of each chromosome.
Why is this?
So that when the egg and sperm combine, they’ll form a cell with the diploid number of chromosomes.
What type of body cells do humans have?
Diploid cells
How many divisions does meiosis involve?
2
Explain the process of meiosis ?
1) DNA replicates and curls up to form double armed chromosomes.
2) after replication the chromosomes arrange themselves into pairs.
3) In the first division these pairs split up, the chromosomes In each pair move to opposite sides of the poles of the cell. Each new cell ends up with a mixture of your mum and dad’s chromosomes, but only half the usual amount of chromosomes
4) the second division of meiosis is like mitosis, the chromosome splits in half and one arm ends up in each new cell
5) you have now ended up wit 4 new cells, two after the first division and then they split leaving you with 4
Haploid?
Half a set of chromosomes
Diploid?
Full set of chromosomes
What does meiosis result a lot in within species?
Genetic variation
What do sperm cells have?
Nucleus, mitochondria, tail, head
Explain the process of mitosis?
1) DNA replicates
2) DNA coils up to form double armed chromosomes
3) the form a straight line down the centre of the cell
4) they are pulled apart to opposite sides of the cell by cell fibres
5) the cytoplasm divides creating two cells that are genetically identical
What is mitosis?
Cell division where body cells are made
